1. Field of the Invention
The present invention relates to photographic printing systems. In particular, the present invention is an improved film guiding apparatus used in conjunction with film cleaning apparatus to permit the film cleaning apparatus to be used both for first-run and photographic reprint production.
2. Description of the Prior Art
In commercial photographic processing operations, very high rates of processing must be achieved and maintained in order to operate profitably. In order to permit efficient automatic processing, orders containing films of similar type and size are typically spliced together for developing. As many as 500 to 1,000 rolls of twelve, twenty, twenty-four and thirty-six exposure film of the same type and size may be spliced together for processing and printing purposes.
After developing the photographic images contained in the film originals (generally negatives) are printed in an edge-to-edge relationship on a continuous strip of photosensitive paper by a photographic printer. The photographic printer causes high intensity light to be passed through the negative and imaged on the photographic print paper to expose the photographic emulsion layers of the paper. The print paper is subsequently processed to produce a print of the image contained in the negative.
The type of large-scale production is well suited to original or first-run production of photographic prints in which the film may be spliced to form a continuous roll. In the past, however, it has not been particularly well suited to production of reprints, where the customer has already received prints and has decided that he wishes to have additional prints made of certain negatives. Unlike first-run productions, making of reprints has typically not been highly automated.
There are several reasons why reprints require special, less efficient handling. First, when reprints are ordered, the negatives generally have already been cut into short segments of three or four frames each, which are more difficult to handle than the longer film strips encountered in first-run production printing. Second, the customer may only desire reprints from one frame of a particular segment. This is unlike first-run production in which a print is typically made from every printable negative on the strip. Third, often multiple prints rather than just a single print are desired from one or more negatives on a segment. Fourth, no extra non-printing area on the film is normally available to which a splice may be made. Fifth, reprints are requested from a much wider variety of film types than are typically encountered in first-run production. This is because most first-run production involves recently purchased and exposed film, while reprints may be from films which were purchased many months or even years earlier.
Because of these problems, making of reprints has often been handled on a manual or semi-automatic basis, and often on a different printer from the high speed first-run production printers on which it may be impossible to reproduce identical print color balance. As a result, the quality of reprints often differs from first-run production prints. The lower quality of reprints in comparison to first-run production prints is a source of customer dissatisfaction.
In order to overcome some of the problems of making reprints, and to provide more efficient automated printing of reprints, systems have been developed in which the individual segments of negatives (usually three or four frames each) from which reprints are to be made are temporarily attached to a long paper strip or "tab". While the "tabbing" of short film segments permits automated handling of reprints on a high speed printer, it has also presented some unique problems which are not present with first-run production. One of these problems is the fact that the film segments are attached to the paper tab only along one edge. As a result, the opposite edge of the film segment is uncontrolled, and has a tendency to get caught and cause jamming of the paper tab and film.
In many photographic printers used for first-run production printing, film cleaning apparatus is provided which removes fine dust and other foreign materials from the photographic film prior to printing of that film. Since photographic films are dielectric materials, there is a tendency for static electric charges to be developed on their surfaces during handling. These static electric charges tend to attract dust to the film surfaces. If this dust is not removed prior to the printing, the dust particles of the negative may appear as imperfections in the resulting print. One particularly successful type of film cleaning device is the 3M Film Cleaner sold by Minnesota Mining and Manufacturing Company. U.S. Pat. No. 3,644,953 by Christiansen describes a film cleaning apparatus of this type, which has a pair of support members in opposed relationship which define a nip. Two lengths of soft, lint-free wiping cloth extend through the nip and form a part of the path of the film through the film cleaner. In addition, a nuclear ionizing device is typically provided to ionize the air along the path and neutralize static electric charges on the film.
It is equally important to provide film cleaning of the film segments attached to a paper tab in a photographic reprint system. Difficulties have been encountered, however, when attempts have been made to use conventional film cleaning apparatus in photographic reprint systems. The short film segments which are attached to the tab along only one edge have presented problems in feeding through the conventional film cleaning apparatus. The "tabbed" film segments have tended to cause jamming, tearing of the tab, or separating of the film segments from the tab.